US8926131B2 - Solid state light with aligned light guide and integrated vented thermal guide - Google Patents

Abstract

A light with integrated light and thermal guides, and having solid state light sources such as LEDs. The light guide includes a material having a first surface and a second surface opposite the first surface and forming an interior volume. The light guide is coupled to the LEDs for receiving and distributing light from them through the first surface, and the light is transported through the light guide until the light is extracted from the first or second surface. The light guide can include alignment features such as fiducials that mate with a base. The thermal guide is contained within the interior volume and integrated with the light guide for providing thermal conduction from the LEDs for cooling the light. The thermal guide can be vented to provide for internal cross flow of air for the cooling.

Description

BACKGROUND

The energy efficiency of lighting has become an important consideration in industrial, consumer, and architectural lighting applications. With the advances in solid state light technology, light emitting diodes (LEDs) have become more energy efficient than fluorescent lights. Further, the marketplace has a large established fixture base for Edison, fluorescent and high intensity discharge lights. These types of applications present a significant technical challenge for LEDs due to their inherent point source nature, and the need to operate the LEDs at relatively low temperatures. Today there are many solutions addressing these issues, including fans, thermal sinks, heat pipes and the like. However, these approaches limit the applications by adding complexity, cost, efficiency loss, added failure modes, and an undesirable form factor. The need remains to find a solution that can provide optical and electrical efficiency benefits, at attractive manufacturing costs and design.

SUMMARY

A light with integrated light and thermal guides, consistent with the present invention, includes at least one solid state light source, a light guide, and a thermal guide. The light guide includes a material having a first surface and a second surface opposite the first surface and forming an interior volume. The light guide is coupled to the solid state light source for receiving and distributing light from the solid state light source through the first surface, and the light is transported through the light guide until the light is extracted from the first or second surface. The thermal guide is at least partially contained within the interior volume and integrated with the light guide for providing thermal conduction from the solid state light source for cooling the light.

The light guide can include one or more of the following features: alignment features such as fiducials that mate with a base; spacers extending along a portion of at least one of the light guide surfaces; and multiple portions mated together with interlocking features.

The thermal guide can include one or more of the following features: apertures to provide for internal cross flow of air; and an internal core with an asymmetric shape to provide for air flow across the core.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the invention. In the drawings,

FIG. 1 is an exploded perspective view of an LED light with a light guide and thermal guide;

FIG. 2 is a perspective view of the light ofFIG. 1 as assembled;

FIG. 3 is an exploded perspective view of an aligned light guide with an integrated vented thermal guide;

FIG. 4 is a side view of the light guide and thermal guide ofFIG. 3 as assembled;

FIG. 5 is a side sectional view of the light guide and thermal guide ofFIG. 3 as assembled;

FIG. 6 is another side sectional view of the light guide and thermal guide ofFIG. 3 as assembled and illustrating asymmetric internal cross flow or air across the thermal guide;

FIG. 7 is another side sectional view of the light guide and thermal guide ofFIG. 3 as assembled and rotated ninety degrees from the view ofFIG. 6; and

FIGS. 8A and 8B are diagrams of a light extraction pattern for the inside of the top and bottom portions, respectively of the light guide.

DETAILED DESCRIPTION

Solid State Light

FIG. 1 is an exploded perspective view of asolid state light10.FIG. 2 is a perspective view oflight10 as assembled. The perspective view inFIG. 2 is looking at the side and top oflight10, which is generally symmetrical from a side view.Light10 includes a light guide comprised of upper andlower portions12 and14, an integratedthermal guide16, a decorativelight ring section18 containing alight circuit24 having solid state light sources such as LEDs, abase portion20, and abase22 for electrical connection to a power source such as via conventional light sockets.Base22 can be implemented with an Edison base to be secured within a corresponding light socket, andbase portion20 can be implemented with an insulator in contact withbase22. Although the light guide is shown as having two portions, it can alternatively have more than two portions or be composed of a single continuous piece of material. Also, the light guide can be configured to form an interior volume, such as by having a bulb shape as shown.

As illustrated inFIG. 2,upper portion12 mates withlower portion14 to form the light guide, andlower portion14 mounts tolight ring18 in order to optically couple with solid state light sources onlight circuit24.Thermal guide16 connects withlight ring18 andbase portion20 in order to draw and dissipate heat from the solid state light sources. As shown inFIG. 1,thermal guide16 has a central core connected with external metal fins, which can conform to the shape of the light guide and be located at least partially within the interior volume formed by the light guide. As shown inFIGS. 1 and 2, anair passage11 inupper portion12 along withapertures17 inlight ring18 allow air flow acrossthermal guide16

Adriver circuit26, on a printed circuit board or flexible circuit, is mounted in the central core ofthermal guide16 such as within a slot in the thermal guide. When mounted,driver circuit26 is electrically connected with solid state light sources onlight circuit24 andbase22.Driver circuit26 receives power from a power supply, typically a high voltage AC power source, viabase22 and provides the required voltages and currents to drive the solid state light sources.Driver circuit26 can be thermally coupled to the thermal guide in order to help cool the electronic components.

Examples of solid state lights, including lights using LEDs, are described in the following, all of which are incorporated herein by reference as if fully set forth: U.S. Patent Application Publication No. 2011/0032708; U.S. patent application Ser. No. 12/960,642, entitled “Solid State Light with Optical Guide and Integrated Thermal Guide,” and filed Dec. 6, 2010; and U.S. patent application Ser. No. 13/435,224, entitled “Electrical Connectors for Solid State Light,” and filed Mar. 30, 2012.

Aligned Light Guide and Vented Thermal Guide

In an alternative embodiment,FIGS. 3-7 illustrate preferred light guide and thermal guide constructions for the solid state light. In particular,FIG. 3 is an exploded perspective view of an aligned light guide with an integrated vented thermal guide.FIGS. 4 and 5 are side and side sectional views, respectively, of the light guide and thermal guide ofFIG. 3 as assembled.FIGS. 6 and 7 are other side sectional views, rotated ninety degrees from one another, of the light guide and thermal guide ofFIG. 3, illustrating asymmetric internal cross flow of air across the thermal guide.

In this alternative embodiment, the light guide includes atop portion30 andbottom portion32.Top portion32 includesside apertures34 and aregion36 next to an injection molding gate whentop portion32 is molded. When installed,bottom portion32 includes a bottom edge coupled to the solid state light sources inlight circuit24 for receiving and distributing light from the solid state light sources through a surface of the top and bottom portions. When installed, the bottom edge ofbottom portion32 fits withinlight ring18.

Anedge46 oftop portion30 mates with anedge44 ofbottom portion32 through interlocking mating features. In particular,edge46 includes a v-shaped protrusion that mates with a v-shaped groove on edge44 (seeFIGS. 5-7). The interlocking mating features provides for alignment oftop portion30 withbottom portion32 such that their exterior surfaces are at least substantially in alignment. Although a v-shaped groove and protrusion are shown, the interlocking mating features can have other shapes that provide for alignment of the light guide portions. With top andbottom portions30 and32 mated together, they can be secured with an adhesive betweenedges44 and46 such as an optically clear adhesive.

Bottom portion32 of the light guide also includes features for aligning it withlight ring18. In particular,bottom portion32 includes a plurality offiducials38 that align tolight ring24. Thelight guide32 aligns to thetop24 andslots40 on light ring18 (seeFIGS. 3 and 4). In addition to alignment, the mating offiducials38 withslots40 can prevent unwanted twisting or rotation ofbottom portion32 inlight ring18.Fiducials38 can be implemented with any shape of protrusion that mates with recesses inlight ring18. Alternatively, fiducials38 can be implemented with any shape of recess that mates with protrusions inlight ring18.

Bottom portion32 also includes a plurality of spacers (ridges)42 extending along a portion of the interior or exterior surfaces of it.Spacers42 preferably extend from an edge ofbottom portion32 along a part of the exterior surface of it (seeFIG. 3). Whenbottom portion32 is aligned withinlight ring18, spacers create a gap betweenbottom portion32 andlight ring18.Spacers42 can also be present on the interior surface ofbottom portion32 creating a gap betweenbottom portion32 andthermal guide50. When the recess is lined with a reflective film, spacers42 can help prevent wet-out of the film. An example of such as reflective film is the Enhanced Specular Reflector film product from 3M Company.

In this alternative embodiment, the thermal guide includes atop shell48 with an innertop core56 and abottom shell50 with aninner bottom core58.Top shell48 fits within and conforms to a shape oftop portion30 of the light guide.Top shell48 includesside apertures52 aligned withapertures34 and optionally atop aperture54 aligned withregion36. The alignment of the thermal guide apertures with the light guide apertures provides for air flow through the light for cooling of it.

Bottom core58 includesfins60 that mate with slots on the inside ofbottom shell50. Aninner slot62 inbottom core58 is used for holding and aligning a driver circuit board64 (seeFIGS. 6 and 7). The base ofbottom core58 can be press fit to light ring18 (seeFIG. 6).Base portion20 can be implemented with plastic and forms an insulator insidebase22.Base portion20 can be snap fit to light ring18 (seeFIG. 6).Bottom core58 can include a potting compound providing for thermal conduction from the driver circuit board. The exterior surfaces oftop shell48 andbottom shell50 can be powder coated with a high gloss super white coating to provide a reflective surface behind the inner surface of the light guide. The components of this thermal guide can be implemented with a metallic material, for example aluminum.

Bottom core58 has an asymmetric shape to accommodate a shape of the driver circuit board and provide for asymmetric air flow across the core.FIG. 6 illustrates air flow as represented byarrows66 and68. As represented byarrow68, air flow is provided throughapertures34 and52, betweenfins60, and along a side ofbottom core58. As represented byarrow66, air flow is provided throughapertures17, betweenfins60 through the bottom ofbottom shell50, and along a side ofbottom core58. The air flow occurs across the sides of thebottom core58 with one of the sides being shown inFIG. 7, which also illustrates how the shape ofdriver circuit board64 conforms to a shape ofbottom core58. The use of an asymmetrically shaped thermal guide core to house the driver circuit board provides for air flow through the light and across the thermal guide core whether the light is mounted vertically or horizontally, or at an angle between those two positions. Air can also flow fromaperture34 to anopposite aperture34 when the light is mounted vertically.

FIGS. 8A and 8B are diagrams of a segment of a light extraction pattern for the inside of the top and bottom portions, respectively of the light guide. This segment of the light extraction pattern can be duplicated around the inside surface of the light guide. This extraction pattern can be milled into a light guide mold using a three-axis mill, which results in the pattern being a distribution of shapes from a nearly spherical shape progressively changing to a teardrop shape. This pattern helps prevent interferences when the light guide is made through a molding process. The light guide is preferably composed of acrylic with this light extraction pattern formed on its interior surface. This light extraction pattern can facilitate a desired light distribution.

In the above description, the labels “top” and “bottom” for the light guide and thermal guide components are used for reference purposes only, since the light can be installed in different positions.

Claims (11)

The invention claimed is:

1. A light, comprising:

at least one solid state light source;

a light guide comprising a material having a first surface and a second surface opposite the first surface,

wherein the second surface forms an interior volume, the light guide has a bottom edge coupled to the solid state light source for receiving and distributing light from the solid state light source through the first surface, and the light is transported through the light guide until the light is extracted from the first or second surface of the light guide,

wherein the light guide includes a plurality of spacers extending along a portion of at least one of the first or second surfaces; and

a section containing the solid state light source and coupled to the light guide, wherein the spacers are located on the first surface of the light guide adjacent the section, and the spacers create a gap between the light guide and the section.

2. The light ofclaim 1, further comprising a thermal guide at least partially contained within the interior volume and integrated with the light guide for providing thermal conduction from the solid state light source for cooling the light.

3. The light ofclaim 1, wherein the light guide is composed of acrylic.

4. The light ofclaim 1, further comprising extraction features on the second surface of the light guide.

5. The light ofclaim 1, wherein the light guide has a top portion and a bottom portion mated together with interlocking features.

6. A light, comprising:

at least one solid state light source;

a light guide comprising a material having a first surface and a second surface opposite the first surface,

wherein the second surface forms an interior volume, the light guide has a bottom edge coupled to the solid state light source for receiving and distributing light from the solid state light source through the first surface, and the light is transported through the light guide until the light is extracted from the first or second surface of the light guide,

wherein the light guide includes a plurality of spacers extending along a portion of at least one of the first or second surfaces;

a base for connection to a power supply; and

a section having a first side coupled to the base and having a second side opposite the first side and coupled to the light guide,

wherein the light guide has a plurality of fiducials, proximate the bottom edge, that mate with the section.

7. A light with integrated light and thermal guides, comprising:

at least one solid state light source;

a light guide comprising a material having a first surface and a second surface opposite the first surface,

wherein the second surface forms an interior volume, the light guide has a bottom edge coupled to the solid state light source for receiving and distributing light from the solid state light source through the first surface, and the light is transported through the light guide until the light is extracted from the first or second surface of the light guide,

wherein the light guide includes a plurality of spacers extending along a portion of at least one of the first or second surfaces;

a thermal guide at least partially contained within the interior volume and integrated with the light guide for providing thermal conduction from the solid state light source for cooling the light,

wherein the thermal guide has an exterior shell with a plurality of apertures providing for air flow through the shell; and

a reflective coating on an exterior surface of the exterior shell.

8. A light with integrated light and thermal guides, comprising:

at least one solid state light source;

a light guide comprising a material having a first surface and a second surface opposite the first surface,

wherein the second surface forms an interior volume, the light guide has a bottom edge coupled to the solid state light source for receiving and distributing light from the solid state light source through the first surface, and the light is transported through the light guide until the light is extracted from the first or second surface of the light guide,

wherein the light guide includes a plurality of spacers extending along a portion of at least one of the first or second surfaces; and

a thermal guide at least partially contained within the interior volume and integrated with the light guide for providing thermal conduction from the solid state light source for cooling the light,

wherein the thermal guide has a internal core with an asymmetric shape providing for air flow across the core.

9. The light ofclaim 8, further comprising a driver circuit for providing power to drive the solid state light source, wherein a shape of the driver circuit conforms to a shape of the internal core.

10. The light ofclaim 8, further comprising fins on an exterior surface of the internal core.

11. The light ofclaim 8, wherein the thermal guide has an exterior shell with a plurality of apertures providing for air flow through the shell.

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